[zerokool]

i was contimplating your specd' TC so this is intresting.

like you im also coming from a 2.7 do you think the gearing is changing the hwy ide rpm's? lowering them?

whats the specs on the stock mamby(TC)? low stall id assume.

just my first thoughts.

[EagleESI]

IF I understand Tq Converters correctly, the stall speed is the rpms in which the highest amplification of tq happens. Noty actual "lockup" I do not believe with these cars having a electronically controlled Lock up should you be seeing any slippage below a given rpm at highways speeds.

I know on my car, I will start seeing lock up after 40mph in 4th gear. Approx 1200-1350 rpms. At highway speeds though there should be lockup unless you downshift or change gears with the tcm disengages the lock up during shifts. However in the Prowler TCm I noticed alot more Tq lock up at lower speeds and with giving it gas at high speeds vs stock A/s TCM.


So in short, a higher stall tq converter for our cars should not in any major way the electronic tq lock up management.

[dodgebob68]

The rpm's would be the same since thats dependent on the trans not the engine, the trans gearing in the 2.7 is 3.89 I believe and 3.66 behind the 3.5. There is where you would see a difference, all other factors being the same. Mine is a 3000 rpm stall speed.

[dodgebob68]

The way I understand it is the same as you have stated. Here's whats strange, unless the TC electronic control is totally different than any other Mopar I've ever seen, or attached or activated somewhere behind the TC in the trans itself, there is no electrical connection going on with my TC. Maybe thats because its custom built to my specs, but I see no way there's any lockup (electronically controlled) anywhere. It's the most conventional appearing TC just about like what you'd find in an old small block 727. There is almost certainly some sort of mechanical lockup since I'm only turning max 2500 rpm at 70 to 75.

That being said, there is still a slight and mildly noticeable surge, (at least by ear, a difference in exhaust tone if not an increase in rpm) when its locked on cruise at highway speeds. I attribute it to the TC. Could be anything else in the world, just what I'm surmising. Come to think of it, there was noting connected to the stock one I pulled out. How does it work then?

[zerokool]

i didnt want to say anything being a learn-er, but i didnt recall connection(s) on my TC either. just on or off.

[Dirdy]

Torque converter lock-up is done hydraulically i believe. It just pops a clutch and locks the inside of the tc to the shaft physically. It only activates at certain speeds under light load.

[EagleESI]

In the 42le is controlled using fluid pressure that is electronically controlled. If there was slippage or of the computer could not control lockup than an error code would be set. Having a custom built Tq does not change this. They still use a stock design but I would imagine the blades are tuned diff for a greater stall speed. However the lockup function will remain the same and its control.

The tcm will allow tc slippage for smoother engagements and shifts. In the special and prowler tcm the tcc management is harsher aka less slippage along with clutch engagement and disengagement for a more performance feel. I can dive into chewievettes factory book on 42le for clarification of needed.

[peva]

This is further than I've read before into this subject, but in agreement with what DIRDY and EAGLEESI said, see the following in the '02 FSM (similar info. in other year FSM's):

From p. 21-148
The torque converter clutch is hydraulically operated and controlled by the TCM. It consists of a piston and a frictional disc that form a direct mechanical link between the impeller and turbine when slippage is inefficient or unnecessary.

See item 5 in Fig. 392 on page 148 and item 15 in Fig. 1 on page 21-3. Read description of Test Five at bottom of p. 21-6. See transaxle schematics and diagrams on pp. 21-148 - 21-160.

[dodgebob68]

Thank you all for the explanation. I am not a transmission guy. Engines yes...transmissions get shipped out to professionals.

[dodgebob68]

Well, time for a stroker update. Its been well over six months, I still haven't run the nitrous yet, the trans is still banging out the gears strong, the engine hasn't grenaded, but I'm working on a super secret long ram intake with a big throttle body. I have never been able to get the fuel controller programmed right, I don't have the patience to keep trying to write a fuel map (I'm not a rocket scientist nor a patient man), so the MAP is running in stock configuration. Haven't been on a dyno yet, nor the strip to get a 1/4 mile time. Thinking of adding a newer and bigger cold air intake (never did get the scoop sealed to the intake pipe, I just let the air flow over the engine to help cool underhood. Thinking of adding a water/methanol injector to cool the intake charge, saw it make a 35 hp difference on a turbo intercooled Mopar, wondering if it will give the 4.0 a slight boost. If nothing else it will steam clean the valves! Couple street races against stangs and tuners have left them embarrased and wondering. I get a lot of looks when I roll up beside someone who knows engines and they see and hear the cam rumble. And a lot of "What do you got in that?" I just smile and tell em its an old slant six with two plug wires missing thats why it runs so lumpy.

[Firemnted]

Nice

[flipfloptrep]

How much you think you getting at the wheels?

[dodgebob68]

Thank you.

[dodgebob68]

Really hard to guess... it will light the tires at will, and torque steer will move you over sometimes as much as a whole lane. You have to have the wheels pointed straight ahead or you never know where you will end up headed. Maybe 200 to 225 h.p.? That would be a wild guess. I figure conservatively having driven a lot of of Mopar racin type motors, that its about 325 at the crank. Max loss thru the drivetrain of 1/3 would put it at 200 or slightly better at the wheels. Remember that it makes way more torque being a stroker, and this thing is a torque monster. Another wild guess, but I'm gonna say its well above 300 in lb./ft/ of torque. I can say that is rolls out faster than any small block Mopar I've ever had, and is on comparison to my 383 powered 66 Belvedere.

[CaptainMorgan]

You're doing all this on the stock ECM right?